Tetracyclines skin tests

Diagnosis of Q fever is performed by serologic testing. Treatment with tetracyclines is effective. Prevention is possible with a formalin-killed, whole-cell vaccine, but prior skin testing to exclude immune individuals is necessary to avoid severe local reactions to the vaccine. A Q fever vaccine is licensed in Australia, but not in the United States, where all Q fever vaccines are investigational. 

Skin tests with various tetracycline compounds in different concentrations have been performed by many clinicians. Unfortunately, non-sensitizing conjugates of tetracyclines with small polypeptide carriers are not available. This is mainly due to our inadequate knowledge of the haptenic determinants responsible for tetracycline allergies. Therefore no effective diagnostic skin tests exist at present. 

For routine skin testing, tetracycline solutions in concentrations of 0.05-0.5 mg/ml for scratch and intracutaneous tests and 10 mg/ml for patch tests have been used. Positive results were obtained in some cases of highly sensitized patients. Zelger and Seidl (1969) obtained a positive scratch test with oxytetracycline in a highly sensitized nurse. Fellner and Baer (1966) reported a positive skin test of the immediate type in a penicillin- and tetracycline-sensitive patient using intracutaneous application of tetracycline. Patch tests gave positive reactions more readily, especially among medical staff and factory workers (Korossy 1976). 

Direct skin contact of the veterinarian with animal medications has probably diminished since the 1970s in many countries. Antibiotics (and other medications) used in veterinary medicine and also animal feed are mainly the same as in human medicine, e.g., penicillins, cephalosporins, macrolides, tetracyclines, quinol-ones, sulfas, trimethoprim, antifungals. In addition, other substances have been used in animals only, e.g., penethamate, tylosin, spiramycin, furazolidone. Many antimicrobials are contact sensitizers and may cause contact dermatitis at low concentrations. No routine series for patch testing can be recommended because of the risk of active sensitization. Patch testing should be done with the particular medications with which the veterinarian has been in contact directly or via fodder. Contact urticaria from several antibiotics and disinfectants has also been reported (Hannuksela 1997b Kanerva 1997). 

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